Verify a download before you open it.

What the result proves

A checksum is a compact fingerprint of every byte in a file. The same input produces the same 64-character SHA-256 value.

Find the expected hash on SlicerShelf

SlicerShelf shows a SHA-256 value only when the release source supplies one. Never compare against a value invented from the file you already downloaded.

1. Open the slicer’s release page and select the exact operating-system package.
2. Look beneath the filename for “SHA-256” and copy the full value.
3. Return here, select the downloaded file and paste that value into the comparison field.
4. Open the file only when the calculated and expected values match.

How SHA-256 verification works

The browser reads the complete file and passes those bytes to the Web Crypto digest function. A one-byte change produces a different result with overwhelming probability.

A checksum confirms integrity, not authorship. Its value depends on where the expected hash came from; use the publisher’s release page or the source recorded by SlicerShelf.

Your file stays on this device

The file picker grants this page temporary read access to the file you choose. The verifier does not send the filename, contents or calculated checksum to SlicerShelf.

Closing or reloading the page discards the selected file and result. The browser may still keep its normal local history and cache for the page itself.

Practical limits

• Web Crypto calculates the digest after the browser has read the file into memory. This page therefore caps files at 512 MiB to avoid exhausting memory.
• A match cannot tell whether the publisher’s own file is safe, signed or appropriate for your printer. It only confirms that both byte sequences correspond.
• If no trusted expected SHA-256 is published, a checksum you calculate yourself is still useful for detecting later changes to your own copy.